Vibratory parts feeders are commonly known apparatuses for providing oriented parts from a mass of disoriented parts, for transporting parts along a processing path, and/or for feeding and maintaining a predetermined quantity of parts to a downstream parts orienting feeder. A common requirement of any of the foregoing parts feeders is a drive unit operable to impart the necessary vibratory feed motion to a parts container operatively associated with the drive unit.
In accordance with one known class of vibratory parts feeders, a vibratory bowl is mounted to a suitable drive unit wherein the drive unit is typically operable to urge parts upwardly along a helical parts path of the bowl by vibrating the bowl both axially along, and rotationally about, its central axis. In the design of such a vibratory parts feeder, an established industry practice is to attach the feeder bowl to a top member of the drive unit, wherein the top member and a stationary base member of the drive unit are interconnected by a plurality of drive springs. Vibratory action is created at the base member, by suitable means, which is transferred to the top member via the drive springs. By establishing an appropriate vibratory direction, and properly positioning the drive springs accordingly, the feeder bowl is made to vibrate in either an upwardly clockwise or upwardly counter-clockwise direction. Parts within the feeder bowl are then correspondingly transported upwardly along the helical parts path to a bowl exit location.
An example of one known vibratory drive unit 15 for use with a vibratory parts feeder 10 is shown in FIG. 1. Referring to FIG. 1, vibratory drive unit 15 includes a top member 12 connected to a bottom member 14 via a number of drive springs 16. Top member 12 includes a number of spring mounting members 18 formed integrally therewith, which members typically include opposing spring mounting faces 20 and 22. Bottom member 14 defines corresponding spring mounting faces 24 and 26 therein. Springs 16 are mounted between spring mounting faces 20 of top member and spring mounting faces 24 of bottom member 14, as shown in FIG. 1, for vibration of top member 12 relative to bottom member 14 in an upward clockwise direction. Springs 16 may alternatively be connected between spring mounting faces 22 of top member 12 and spring mounting faces 26 of bottom member 14 for rotation of top member 12 relative to bottom member 14 in an upward counter-clockwise direction. In so doing, vibratory drive unit 15 typically includes a striker plate 28 connected to top member 12, and an electromagnetic driver 30 mounted to bottom member 14. Electromagnetic driver 30 is typically periodically energized to attract striker plate 28 thereto, thereby imparting the vibratory drive motion to top member 12 through springs 16 as is known in the art.
While the foregoing vibratory drive unit structure is widely used and satisfactorily provides for bi-directional operation thereof, it has several drawbacks associated therewith. For example, spring mounting faces 20, 22, 24 and 26 are formed integrally with top member 12 and bottom member 14 respectively. Typically, such spring mounting faces have a bore therethrough for engaging a fastener used to mount springs 16 thereto. If any damage occurs to faces 20-26, or the bores defined therein, either due to accident or normal wear and tear, the entire top member 12 or bottom member 14 must be replaced for continued operation of vibratory drive unit 15. Such replacement can be costly and wasteful, particularly if only one spring mounting face, or bore, is damaged, and the remaining spring mounting faces and corresponding bores are in good condition. As another example, providing vibratory drive unit 15 with bi-directional operation requires the number of spring mounting faces of top member 12 and bottom member 14 to be doubled over that required for uni-directional operation. Such a requirement adds significantly to the processing time and costs of fabricating top member 12 and bottom member 14.
Designers of vibratory parts feeders have utilized several approaches in attaching a feeder bowl to a vibratory drive unit, such as drive unit 15. One such prior art approach is shown with respect to vibratory parts feeder 10 of FIG. 1. Referring to FIG. 1, a feeder bowl 32 is attached to the top member 12 of vibratory drive unit 15 via a number of clamp nuts 40. Vibratory bowl 32 includes a side wall portion 34 which extends downwardly beyond bottom bowl surface 36, thereby defining a flange portion 38. Fasteners 42 extend through clamp nuts 40 into top member 12 to thereby secure flange portion 38 between a vertical wall 12a of top member 12 and clamp nuts 40.
Yet another known approach for attaching a feeder bowl to a vibratory drive unit is shown with respect to vibratory parts feeder 50 of FIG. 2. Referring to FIG. 2, vibratory bowl 52 is attached to top member 12' of vibratory drive unit 15 via a number of fasteners 42. Vibratory bowl 52 includes a side wall 54 which extends downwardly below a bottom surface 56 of bowl 52 to form a flange 58. Fasteners 42 extend through flange 58 into top member 12' such that flange 58 is clamped between vertical side wall 12a' of top member 12' and fasteners 42.
Another known approach for attaching a feeder bowl to a vibratory drive unit is shown with respect to the vibratory parts feeder 60 of FIG. 3. Referring to FIG. 3, a vibratory bowl 62 is mounted to top member 12" of vibratory drive unit 15 via a number of fasteners 72. Vibratory bowl 62 includes a side wall 64 which extends downwardly below a bottom surface 66 of bowl 62 to form a flange portion 68. A plate 70 is attached to the bottom surface of bowl 62, typically via welding, and extends outwardly to flange portion 68. A number of fasteners 72 extend upwardly through top member 12" and into engagement with plate 70 to thereby attach bowl 62 to top member 12".
Still another known approach for attaching a feeder bowl to a vibratory drive unit is shown with respect to the vibratory parts feeder 80 of FIG. 4. Referring to FIG. 4, a feeder bowl 82 is mounted to a top member 12'" of vibratory drive unit 15 via a number of fasteners 92. Vibratory bowl 82 includes a side wall 84 extending below a bottom surface 86 of bowl 82 to form a flange portion 88. A number of lugs 90 are attached to the bottom surface 86 of bowl 82 and to a portion of inner surface 88a of flange portion 88 adjacent thereto. Vibratory bowl 82 is then mounted to vibratory drive unit 15 such that a gap G is defined between bottom bowl surface 86 and top member 12'". A number of fasteners 92 extend upwardly through top member 12'" and engage lugs 90 to thereby secure vibratory bowl 82 to top member 12'" of vibratory drive unit 15.
While the foregoing techniques for mounting a feeder bowl to a vibratory drive unit have been used extensively in the past, each have drawbacks associated therewith, particularly when used with large feeder bowls and corresponding drive units (e.g., feeder bowls having diameters in excess of approximately 18 inches). For example, the clamp nut and flange mount techniques shown and described with respect to FIGS. 1 and 2 have a tendency to twist and eventually fracture the flange portion of the feeder bowl. The bottom plate structure of FIG. 3 alleviates this problem, but requires plate 70 to have substantial thickness to provide adequate engaging surfaces for engaging fasteners 72 in order to avoid stripping fasteners 72 during operation of the parts feeder. Unfortunately, increasing the thickness of plate 70 necessarily has the undesirable effect of increasing the weight of the vibratory bowl which then results in decreased drive efficiency. While the bowl mounting arrangement of FIG. 4 provides for such increased fastener engaging surfaces without substantially adding weight to the vibratory bowl, this approach reduces the rigidity of bowl 82 in the vicinity of the flange portion 88. Under the tremendous forces present in large vibratory parts feeders, the use of lugs 90 may deform or possibly fracture flange portion 88 within the vicinity of the various lugs 90 during operation of the vibratory parts feeder.
In view of the foregoing shortcomings of prior art vibratory drive units and feeder bowl mounting arrangements, there exists a need for improvement in such areas, particularly with large feeder bowls and corresponding drive units. An ideal vibratory drive unit should be suitably configured so that damage to one or more spring mounting faces does not require replacement of an entire top or bottom member. An ideal feeder bowl mounting arrangement should rigidly secure the feeder bowl to the top member of the vibratory drive unit against rotational forces in either rotational direction, and further against vertical forces due to lifting of the feeder bowl, and should be suitably robust to withstand the tremendous vibrational forces present in large feeder bowl and corresponding vibratory drive unit configurations.